docs: def get_transport_info(self, key: str) -> Any:
          """
          Get extra info from the transport.
          Supported keys:
  
              - ``peername``
              - ``socket``
              - ``sockname``
              - ``compression``
              - ``cipher``
              - ``peercert``
              - ``sslcontext``
              - ``sslobject``
  
          :raises SMTPServerDisconnected: connection lost
          """
          self._raise_error_if_disconnected()
  
          return self.transport.get_extra_info(key)